In recent years, the information recording density of recording media used in magnetic recording devices such as magnetic disk devices (HDDs) has become increasingly high. As the recording density increases, the probability of occurrence of magnetic interference called thermal fluctuation that a recording portion interferes with an adjacent portion of the recording portion becomes higher. In order to prevent magnetic interference, a recording medium may be used in which a recording film is made of a material that is high in coercive force at ordinary temperature. In order to record information on the recording film, a technique has been developed that makes it possible to lower the coercive force at a recording position by increasing the temperature of the recording position with optical heat assistance, thereby to record magnetically the information. This information recording technique is called heat-assisted recording.
In the heat-assisted recording, the quantity of light applied to a recording position is required to be controlled to within a prescribed range. To control the quantity of light applied to the recording position to within a prescribed range, it is necessary to optimize the quantity of light emitted from a light-emitting element at least before recording of information. The light quantity optimization needs to be performed in not only the heat-assisted recording in the magnetic recording devices but also information recording in optical information recording devices which use an optical disc as a recording medium. For example, it is known that light quantity optimization processing called optical power control (OPC) is performed in the case of optical information recording devices using an optical disc. However, few light quantity optimization techniques for the heat-assisted recording in magnetic recording devices are known.
According to the related art, in the entire recording area of a recording medium, a recording area for light quantity optimization processing is provided independently of a data recording area. Therefore, a sufficient data recording area cannot be secured in the entire recording area of a recording medium.